$ git clone -n https://src.fedoraproject.org/rpms/R-readr.git /var/lib/mock/f41-build-1017404-17932/root/chroot_tmpdir/scmroot/R-readr
Cloning into '/var/lib/mock/f41-build-1017404-17932/root/chroot_tmpdir/scmroot/R-readr'...
$ git fetch origin 97d5498112daff675e8289499b5aa234b82ada5a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-readr
 * [new ref]         97d5498112daff675e8289499b5aa234b82ada5a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 97d5498 Eliminate use of obsolete %patchN syntax (#2283636)